An integral aim of any SUDS system, notably under the terms of the WAT category in the Code for Sustainable Homes, is to ensure run-off rates from developed areas match those of the original greenfield site. Attenuation and storage tanks help slow run-off at source. But equally important is control over rates of release to watercourses. Stormcheck has been designed to provide precise, predictable release rates based on local conditions. It's a flow control system comprising of a prefabricated plastic chamber with an integral vortex flow control device. This can be a non-bypass design for sites in which discharge rates cannot be exceeded; a manual bypass design to allow operators to increase flow rates form the surface; or an auto-bypass design that allows for an increase in flow rates if conditions demand it.